A patch clamp technique in electrophysiology is known as a method for measuring an ion channel which the cell membrane possesses. With this patch clamp technique, various functions of the ion channel have been elucidated. The function of the ion channel has been a great interest and applied to development of drugs.
However, on the other hand, since the patch clamp technique as a measuring technique requires an extremely high skill of inserting a fine micropipette into a single cell with a high accuracy, this technique requires a skilled operator. Therefore, this technique is not suitable for an application that requires high-throughput measurement.
Therefore, an automated system, which does not require the insertion of a micropipette into an individual cell and is capable of automatically fixing a cell for measurement only by reducing pressure, has been developing.
FIG. 11 is a sectional view showing a conventional cell electrophysiological sensor. A conventional cell electrophysiological sensor includes sensor chip 102 having continuity hole 101, electrolytic baths 103 and 104 defined by sensor chip 102, and electrodes 105 and 106 disposed in electrolytic baths 103 and 104, respectively.
In this cell electrophysiological sensor, cell 107 and an electrolytic solution are filled in electrolytic bath 103, and the electrolytic solution is sucked by applying pressure from the upper part or reducing pressure from the lower part of continuity hole 101, so that cell 107 can be trapped in an opening of continuity hole 101. Then, for example, a drug is applied from the upper part of cell 107, and the potential difference between electrolytic baths 103 and 104 is measured by electrodes 105 and 106 and analyzed. Thus, the pharmacological reaction of cell 107 can be determined.
Then, such an extremely small sensor chip 102 is inserted into a chip holding part (not shown) such as a plate and a tube and then fixed with an adhesive agent and the like, which can be used as a cell electrophysiological sensor device.
Note here that examples similar to the above-mentioned conventional technology are described in the following patent documents.
However, as mentioned above, in the cell electrophysiological sensor device in which sensor chip 102 is inserted into the chip holding part, a leakage current tends to occur on the side surface of sensor chip 102.
The reason is because the airtightness between the side surface of sensor chip 102 and the chip holding part is low.
That is to say, when sensor chip 102 is joined to the chip holding part with an adhesive agent, unevenness and peeling easily occur in joining. Therefore, the airtightness between sensor chip 102 and the chip holding part becomes low. As a result, a leakage current tends to occur.
[Patent Document 1] Japanese Translation of PCT Publication No. 2002-518678
[Patent Document 2] Japanese Translation of PCT Publication No. 2003-527581